A family of regulatory proteins that deliver signals between many different types of cells in the body has been identified. These regulatory molecules are known as cytokines. Many of the cytokines have been found to control the growth and development and biological activities of cells in the hematopoietic and immune systems. Cytokines have also been identified which are produced by other cell types including fibroblasts and endothelial cells which transmit signals between these cells and a variety of responsive target cells. This family of cytokines is clearly important for maintaining homeostasis and for coordinating the physiological responses to a variety of insults including wounding and infection as well as regulating the immune response [See, for example G. Wong & S. Clark, Immunology Today, 9(5):139 (1988)]. The family of cytokines includes the interleukins, the hematopoietic colony-stimulating factors, the interferons, and the tumor necrosis factors among others. In addition, two subfamilies within the larger cytokine family have emerged that share evolutionary relatedness at the nucleotide level. Members of one of these families share sequence similarity with a cytokine known as macrophage inflammatory protein 1 (MIP-1) [Davatelis, G. et al J. Exp. Med., 167:1939-1944 (1988)], while members of the other family share sequence similarity with a second macrophage inflammatory protein, MIP-2 [Wolpe, S. D. et al, Proc. Nat'l Acad. Sci. USA, 86:612-616 (1988)]. MIP-1 and MIP-2 are cytokines produced by activated macrophages that induce local inflammatory responses when injected subcutaneously in mice. Other polypeptides have been identified through molecular biological approaches which are clearly related to either MIP-1 or MIP-2 but for which biological activities have not yet been identified. Although the function of these molecules is not known, they, like other members of the cytokine family, are likely to be important in various aspects of regulating homeostasis or coordinating physiological responses to wounding, injury, or infection or in the regulation of the immune system.
One member of the MIP-1 subfamily may be the murine JE [Rollins et al, Proc. Nat'l. Acad. Sci. USA 85:3738-3742 (1988)] and its human homologue disclosed herein.